1. Field of the Invention
The invention relates to a light-emitting diode (LED) device and more particularly to LED devices with a lens module having a fluorescent material and methods for fabricating the same.
2. Description of the Related Art
Light-emitting diode (LED) devices are solid-state light sources and have been known for years. The LED devices are based on the recombination of electron-hole pairs in a pn-junction in a semiconductor material which is forward-biased. Advantages of LED devices compared with traditional lamps are lower power consumption and longer lifespan. In particular, because white light LED devices have a high color rendering index (CRI), it has become one of the most popular illuminating devices used.
A white light LED device can be obtained by mixing red, green, and blue lights using a combination of a red light LED chip (or die), a green light LED chip, and a blue light LED chip to form the white light LED device. However, the above three-in-one white light LED device is expensive because it requires three LED chips for different emitted lights. Moreover, the CRI is reduced due to the different light-emitting efficiencies for each of the three LED chips.
In order to address the above drawbacks, a white light LED device has been developed by using a combination of a blue light LED device combined with a fluorescent material, such as a phosphor material. The blue light passes through the fluorescent red and green phosphor material, such that the combination of blue, red, and green lights produces a white light. Currently, such a white light LED device is formed by filling an epoxy resin containing phosphors around a blue light LED chip and then a lens is capped thereon. However, poor uniformity of the filled epoxy resin reduces the light-emitting properties of the LED devices. Another method to form the white light LED device is to fill a transparent protective resin or glue around a blue light LED chip followed by coating an epoxy resin layer containing phosphors thereon and capping a lens on top. However, the coating rate of the epoxy resin layer is slow and it is also difficult to control the uniformity of the epoxy resin layer. Further another method to form the white light LED device is to form a lens on a blue light LED chip followed by coating an epoxy resin layer containing phosphors thereon and covering the lens with a transparent protective resin or glue. However, the coating rate of the epoxy resin layer is also slow and the manufacturing cost is high. Moreover, in the above methods, the blue light LED chips are packaged by chip level packaging techniques, which are time consuming, thereby limiting a throughput for packaging of the blue light LED chip.
Therefore, there is a need to develop a novel LED device capable of addressing the above problems.